Toy building kit

ABSTRACT

A toy building kit has several structural elements. Some of these have at least one undercut groove in an exposed surface and others have at least one coupling head provided on an exposed surface and matingly engageable with the undercut groove. Such coupling heads each comprise a first portion which projects from the respective structural element and which is provided on its free end remote from the structural element with a second portion resembling a section severed from a sphere in a plane which is at least substantially parallel to the general plane of the exposed face.

United States Patent Inventor Artur Fischer Althe'uner Str. 219,Tumlingen, Germany Appl. No. 16,754 Filed Mar. 5, 1970 Patented July 13,1971 Priority Mar. 7, 1969 Germany P 19 11 650.8

TOY BUILDING KIT 10 Claims, 1 Drawing Fig.

US. Cl 46/25 Int. Cl A6311 33/08 FieldoiSearch 46/16, 17,

[56] References Cited UNITED STATES PATENTS 3,484,983 l2/l969 Fischer46/25 X 3,513,589 5/1970 Fischer 46/25 3,513,590 5/1970 Fischer 46/25Primary Examiner-Louis G. Mancene Assistant Examiner-D. L. WeinholdAttorney-Michael S. Striker ABSTRACT: A toy building kit has severalstructural elements. Some of these have at least one undercut groove inan exposed surface and others have at least one coupling head providedon an exposed surface and matingly engageable with the undercut groove.Such coupling heads each comprise a first portion which projects fromthe respective structural element and which is provided on its free endremote from the structural element with a second portion resembling asection severed from a sphere in a plane which is at least substantiallyparallel to the general plane of the exposed face.

TOY BUILDllNG KIT BACKGROUND OF THE [NVENTlON The present inventionrelates generally to toy building kits, and more particularly to toybuilding kits having matingly engageable male and female couplingportions.

lt is a rather conventional expedient in recent years to provide toybuilding kits with matingly engageable undercut male and female couplingportions so that a child mayconnect the structural elements of such akit without necessitating the use of tools, separate connectors or thelike. In one known construction the female coupling portions are'in formof an elongated undercut grooves, and the male coupling portions are inform of coupling projections or coupling heads which are matinglyreceivable in these undercut grooves, and which are similarly undercut.They have a neck or first portion projecting from the respective elementon which they are provided, and carrying at its fee end a head or secondportion which is of polygonal cross section, usually quadratic. Theconnection effected between structural elements provided with suchcoupling portions is good. lt has been found, however, that theinsertion and moving lengthwise of a male coupling portion configuratedin this manner, into a groove which is undercut and which is intended tomate, presents difficulties for children, particularly for relativelyyoung children. With male coupling portions so constructed it is evidentthat the entire width of the coupling portion will immediately fill theinlet end of the groove when insertion is attempted. This means that themale coupling portion must be properly aligned with respect to the inletend, that is to the cross section of the groove, requiring a degree ofskill which frequently is not yet possessed by smaller children. Theproblem becomes aggravated if the male coupling portion has-as isfrequently the case in the interest of obtaining a tighter connection-acertain excess in its cross-sectional dimension over the correspondingdimension of the groove, even if this excess is small. Furthermore, inthis known construction it is intended that when the male and femalecoupling portions mate they are to exert stress upon their respectiveassociated structural elements in a sense urging the same into abutment,that is causing the surfaces on which the male and female couplingportions are respectively provided, to tightly abut one another. This isalso in the interest of obtaining a tight connection between thestructural elements. For this purpose the distance between the surfacefrom which the coupling head projects and the area of the coupling headwhich, when inserted into an undercut groove, contacts the innercircumferential surface of the groove, is slightly smaller than thedistance between the surface in which the groove is provided and theportion of the inner circumferential surface which will be contacted bythe coupling head when the same is inserted. This evidently exerts pullor tension on the structural elements connected with one another.Finally, it has also been observed that if the coupling heads are rathersmall, a young child finds it difficult to align the coupling head withreference to the elongation of the undercut groove in the mannernecessary to effect the entry of the coupling head into the open end ofthe groove. In fact, it is frequently observed that the smaller childdoes not even real ize that such alignment is necessary. On the otherhand, if the coupling heads are larger it is easier for the child torealize that such alignment is necessary, but the danger of tilting orskewing of the coupling head with reference to the groove on insertioninto the same then exists.

Further difficulties have been found, particularly with reference to theuse of such kits by smaller children, in the movement of the onceinserted male coupling head along the groove, as a result of unavoidabletolerance variations. The coupling head may be rather tight in thegroove and difficult to move along the same. On the other hand it may berelatively loose and the connection may then not be as tight as desired.For instance, if the structural elements and/or coupling heads are ofcertain materials, such as wood, it is either entirely impossible tomaintain the necessary manufacturing tolerances or so difficult that itis economically impractical to do so. Added to this is the fact that inthe finished structural element the dimensional tolerances usually varyin dependence upon ambient humidity due to swelling or contracting ofthe material of the element whereby again in undesired manner theseating or mating of the male coupling portions in the female couplingportions is effected. It is thus possible that the coupling head will atone time be relatively loose in a cooperating groove and at another timewill be rather tight, for instance after a model erected has been leftfor a period of time. In fact, swelling due to an increased moisturecontent of the material of the elements can be caused not only byvariations in the ambient humidity, but also by the fact that childrenhave a tendency to place articles into their mouth so that they becomewetted with saliva. There is, finally, the problem that woodthepreferred material ,from which structural elements for kits or toys forsmaller children are made-4s relatively rigid and has little elasticity,so that yielding of the material under the aforemention circumstances isexcluded and cannot provide relief.

SUMMARY OF THE INVENTION It is, accordingly, an object of the presentinvention to overcome the aforementioned disadvantages.

More particularly it is an object .of the present invention to provideart-improved toy building kit which is not possessed of thesedisadvantages.

Still more particularly it is an object of the invention to provide animproved toy building kit having cooperating undercut male and femalecoupling portions, and wherein the male coupling portions can be readilyand without any skill inserted into the female coupling portions, withthe aforementioned difficulties relative to tolerance variations anddimensional variations due to swelling of the material being avoidedwhile the coupling portions yet provide for a tight connection betweenconnected structural elements.

An additional object of the invention is to provide such a kit whereinthe cooperating male and female coupling portions can be readilymanipulated by even small children having as yet little manipulativeskill and inadequately developed coordination.

ln pursuance of the above objects, and others which will become apparenthereafter, one feature of the invention resides in a toy building kitwhich, briefly stated, comprises a first structural element having aplurality of exposed surfaces and being provided in at least one ofthese with at least one undercut groove. A second structural element hasa plurality of exposed faces and is provided on at least one of theexposed faces with at least coupling head which is matingly engageablewith the undercut groove. The male coupling head comprises a firstportion projecting from the exposed face and has a free end remote fromthe latter. A second portion of the male coupling head is provided onand projects from this free end and resembles a section severed from asphere in a plane which is at least substantially parallel to thegeneral plane of the exposed face. A coupling head so configurated abutsagainst the inner circumferential surface of the undercutgroove only ina region which is relatively near to the exposed surface from which thegroove extends inwardly.

The cross section of the secondportion at least is circular. The crosssection of the first portion or neck of the coupling projection may becircular or generally rounded, but it may also be polygonal, forinstance quadratic. Because of the particular configuration of thesecond portion which, as pointed out, is circular in cross section,insertion of the coupling projection into the open end of an undercutcoupling groove provides for self-alignment of the coupling projectionwith reference to the groove, because immediately upon insertion it isnot the entire width of the second portion which fills the groove, butonly after the second portion is received half way in the open end willits full or entire width fill the open end of the groove. Until suchtime the circular outer periphery of the second portion will provide forgradual alignment of the coupling projection with reference to the openend of the groove as the second portion is being inserted thereinto. Onthe other hand, the part-spherical configuration of the second portionassures that the coupling projection can be introduced without anymanipulative skill and with little force into the open end of the grooveeven if it is desired that the relationship between the groove and thecoupling projection be such that the two connected structural elementsbe urged into abutment with one another.

The free end face of the second portion faces away from the face of itsstructural element on which the coupling projection is provided. It islocated in the aforementioned plane which is at least substantiallyparallel to the general plane of the exposed face and is thus is aposition in which it includes with the part-spherical outer surface ofthe second portion a relatively acute angle. Because of this the marginof the second portion in the region of the juncture between this endface and the part-spherical outer surface of the second portion isyieldable and thus permits a compensation for dimensional variations ortolerance variations.

The ability to yield which is desired for the second portion may beenhanced by making the end face of the second portion concavely curvedin the direction towards the exposed face on which the couplingprojection is provided.

According to the invention the part-spherical outer surface of thesecond portion is to contact the inner circumferential surface boundingthe groove only in the region near the exposed surface in which thegroove is provided. Thus, when the male coupling projection is receivedin a cooperating groove, forces acting upon the coupling projection willact upon the latter only in the aforementioned region in which it isdeformable. Thus, if due to dimensional tolerance variations thecoupling projection is shorter than intended in the direction normal tothe exposed face from which it projects, then its marginal zone isinwardly deflected by engagement with the circumferential surface of thegroove. The contact with this surface is springy so that even underthese circumstances the coupling projection can still be readily shiftedlengthwise of the groove without requiring extraordinary force, that isforce which goes beyond what can be expected from a small child, anddespite this a firm and tight connection between the thus-coupledstructural elements is obtained.

The present invention is particularly advantageous with respect torather large coupling projections whose size and massive configurationwould not ordinarily provide -particularly in materials such as wood-thenecessary yieldability which is desired.

If it is desired that once the coupling projection is inserted into acorresponding groove, the two elements be capable of being rotated withreference to one another about an axis defined by the first portion,then the neck or first portion may be generally rounded, such as ofcircular cross section. If, on the other hand, such rotation is to beprevented than it is desirable for the cross section of the firstportion to be polygonal, preferably quadratic.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a diagrammaticillustration showing one embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the FIGURE reference numeral1 identifies a first structural element, of which a building kit maycomprise any desired number. It has a plurality of exposed faces atleast one of which is provided with a projecting male coupling portionor coupling projection 2 which is still to be described in more detail.Reference numeral 4 identifies a further structural element of which thetoy building kit may also comprise a desired number and which isprovided with a plurality of exposed surfaces at least one of which isprovided with an undercut elongated groove 3 of substantially circularcross section, as illustrated. Of course, any of the structural elementsI and 4 may be provided with both the coupling projections 2 and theundercut grooves 3.

The coupling head 2 will be seen to be matingly received in the undercutgroove 3 through whose open end it has been inserted. It comprises afirst portion or neck 6 which projects from the exposed face 5 of theelement 1 and which is formed at its free end remote from the exposedface 5 with a head or second portion 7 resembling a segment cut from asphere on a line which is located in a plane extending in substantialparallelism with the exposed face 5. In other words, if one assumes thatthe portion 7 were to be initially configurated as a sphere, theparticular illustrated configuration of the portion 7 is obtained bysevering the sphere in a plane extending in parallelism or at leastsubstantial parallelism with the exposed face 5 and removing theremainder of the sphere, leaving only the illustrated segment behindwhich constitutes the portion 7. This portion 7 is provided with an endface 8 facing away from the exposed face 5. It will be seen that theportion 7 engages the inner circumferential surface 10 of the groove 3only in a region 9 which is near the exposed surface 8 of the structuralelement 4. In the illustrated embodiment the first portion or neck 6 isof circular cross-sectional configuration and contacts the edges 11 ofthe groove which are bounded by planar surface portions.

It will be appreciated, however, that the inner circumferential surfaceof the groove 3 can also be in form of planar surface portions withoutdetracting from the concept according to the present invention. Thedesired advantages of the present invention are achieved also if thehead or second portion 7 deviates slight-but not significantly-from thepartspherical configuration which has been illustrated in the FIGURE. Inerecting certain model constructions it may be desirable or advantageousto arrest coupled structural elements in certain locations withreference to one another. This can be achieved by configurating thecross section of the first portion 6 so that it is rounded andconstitutes in effect a wedging means, that is by making the crosssection of rounded but noncircular configuration so that, with thecoupling projection 2 inserted into a groove 3, the elements 1 and 4will be turned with reference to one another about an axis defined bythe portions 6 until the same becomes wedged into engagement with theedges 11. If, on the other hand, the cross-sectional configuration ofthe portion 6 is circular as in the exemplary embodiment hereindiscussed, the elements l and 4 can be freely turned with reference toone another whereas, if the cross-sectional configuration of the portion6 is polygonal preferably quadraticany turning movement of the elementsl and 4 with reference to one another is entirely precluded.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in atoy building kit, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What I claim as new and desire to be protected by Letters Patent is setforth in the appended claims:

1. In a toy building kit, in combination, a first structural elementhaving a plurality of exposed surfaces; at least one undercut grooveprovided in at least one of said exposed surfaces; a second structuralelement having a plurality of exposed faces; and at least one couplinghead provided on at least one of said exposed faces and matinglyengageable with said undercut groove, said coupling head comprising afirst portion projecting from said exposed face and having a free endremote from the latter, and a second portion provided on and projectingfrom said free end and resembling a section severed from a sphere in aplane which is at least substantially parallel to the general plane ofsaid exposed face.

2. In a kit as defined in claim 1, said groove having at least one openend, and said coupling head being insertable through said open end indirection lengthwise of said groove.

3. In a kit as defined in claim I, said second portion having a planarsurface directed away from said exposed face.

4. In a kit as defined in claim 1, said second portion having an endfacedirected away from said exposed face and being concave in directiontowards the same.

5. In a kit as defined in claim 1, said first portion having a polygonalcross section.

6. In a kit as defined in claim 5, wherein the cross section of saidfirst portion is quadratic.

7. In a kit as defined in claim 1, said first portion having a roundedcross section 8. In a kit as defined in claim 7, wherein the crosssection of said first portion is circular.

9. in a kit as defined in claim 1, said groove comprising an outerslot-shaped portion extending inwardly from said one exposed surface andbeing bounded by two transversely spaced outer surface portions, and aninner portion bounded by an inner circumferential surface portion makingwith said outer surface portions and being of divergent-convergent crosssection in direction inwardly away from said outer portion; and saidsecond portions being configurated so as to contact said inner surfaceportion only in the region of the juncture of the same with said outersurface portions.

110. in a kit as defined in claim 9, wherein the spacing between saidouter surface portions is greater than the maximum cross-sectionaldimension of said first portion of said coupling head.

1. In a toy building kit, in combination, a first structural elementhaving a plurality of exposed surfaces; at least one undercut grooveprovided in at least one of said exposed surfaces; a second structuralelement having a plurality of exposed faces; and at least one couplinghead provided on at least one of said exposed faces and matinglyengageable with said undercut groove, said coupling head comprising afirst portion projecting from said exposed face and having a free endremote from the latter, and a second portion provided on and projectingfrom said free end and resembling a section severed from a sphere in aplane which is at least substantially parallel to the general plane ofsaid exposed face.
 2. In a kit as defined in claim 1, said groove havingat least one open end, and said coupling head being insertable throughsaid open end in direction lengthwise of said groove.
 3. In a kit asdefined in claim 1, said second portion having a planar surface directedaway from said exposed face.
 4. In a kit as defined in claim 1, saidsecond portion having an endface directed away from said exposed faceand being concave in direction towards the same.
 5. In a kit as definedin claim 1, said first portion having a polygonal cross section.
 6. In akit as defined in claim 5, wherein the cross section of said firstportion is quadratic.
 7. In a kit as defined in claim 1, said firstportion having a rounded cross section.
 8. In a kit as defined in claim7, wherein the cross section of said first portion is circular.
 9. In akit as defined in claim 1, said groove comprising an outer slot-shapedportion extending inwardly from said one exposed surface and beingbounded by two transversely spaced outer surface portions, and an innerportion bounded by an inner circumferential surface portion making withsaid outer surface portions and being of divergent-convergent crosssection in direction inwardly away from said outer portion; and saidsecond portions being configurated so as to contact said inner suRfaceportion only in the region of the juncture of the same with said outersurface portions.
 10. In a kit as defined in claim 9, wherein thespacing between said outer surface portions is greater than the maximumcross-sectional dimension of said first portion of said coupling head.